Test your diagnostic skills in our regular dermatology quiz. What has caused this rash on the trunk and limbs of a pregnant woman who is otherwise well?
A 34-year-old woman presents at 30 weeks’ gestation in her first pregnancy with an intensely pruritic eruption (Figures 1a and b). It has been present for three weeks and is unresponsive to antihistamines. The rash started at her umbilicus and progressed to involve her trunk, arms and legs. Her face, scalp and palmar surfaces are not involved. The rash is characterised by fixed, oedematous, annular lesions that have coalesced on her trunk and limbs. Vesicles have appeared on some lesions.